Developed by Boeing for the U.S. Air Force and U.S. Navy, the Joint Direct Attack Munition (JDAM) guidance tail kit converts unguided, free-fall "dumb" bombs into accurate, all-weather "smart" Guided Bomb Units (GBU). These bombs cost much less than laser or television guided bombs. The tail section contains an inertial navigation system (INS) and global positioning system (GPS) guidance control unit. It easily attaches to either a 2,000-pound BLU-109/-MK-84 bomb to make a GBU-31 or a 1,000-pound BLU-110/MK-83 to make a GBU-32. Target coordinates are located into the aircraft before takeoff; however, if the target moves, the aircrew can manually reset the new coordinates in flight, or onboard aircraft sensors can automatically update them. Once released, the fins guide the bomb as far as 15 miles to the designated target coordinates.